Maroon leaf monkey
|Maroon leaf monkey|
|Maroon leaf monkey range|
The maroon langur, maroon leaf monkey, or red leaf monkey (Presbytis rubicunda) belongs within the order Primate and the family Cercopithecidae. It is found on the southeast Asian island of Borneo and the nearby smaller Karimata. P. rubicunda mostly live in forests at altitudes below 2,000 m. They feed on leaves (36%), .
Distribution and Habitat
Red Leaf monkeys (Presbytis rubicunda) are found in Southeast Asia. They are located in the Danum Valley of Sabah within Northern Borneo. Red Leaf monkeys are endemic to the Borneo island which is part of Malaysia, Indonesia and Brunei. Red Leaf monkeys are within the tropical rainforest of Kalimantan of the Borneo island. Their habitat is dense and has dipterocarp evergreens.
The Borneo island has a healthy tropical rainforest. This island is not only made up of the tropical rainforest, but it also contains shallow swampy areas that is made up of sod containing acidic, decomposed plant matter. The swamp amalgamated along with the rivers nearby. These swampy areas have their seasonal bouts of dry weather but when the wet season comes about, the rivers rises around 2 meters.
Red Leaf monkeys are arboreal primates and spend most of their time in the canopies. They also have a large range in their home size and a population that is lower in density, compare to that of other primates. The main understanding towards this large range and lower population, is to be the relying on trees that are rare.
Red leaf monkeys are herbivores.The main diet that Red Leaf monkeys consumes are fruits, seeds, young leaves, and flowers. They are selective feeders, as food becomes limited they will feed on certain types of plant matter or seeds during their time of abundance. To maintain a balance in their diet, Red Leaf monkeys will consume top soil from termite mounds.
The main feeding time is on young parts of leaves. This feeding time that is mainly on leaves that are young, leads to a decrease of seed and whole fruits intake. The least that are to be consume are flowers. This feed pattern is only seasonally. As the fruit season peaks during June to September, there is an increase of fruit being produced. During this time of abundance, Red Leaf monkeys feed on large amounts of seeds and fruits. During October to June, is when the greatest occurrence of young leaves are being fed on. June is the time when they mostly intake young leaves. During this dry time of the year, Red Leaf monkeys consume more succulent foliage and are decreasing the quantities of seed intake. During the months of March through May, is the seasons for flowers. During the flowering season, they increase their flower intake. There is only one type of flower that becomes a high demand of resource during the month of December. As the raining season insist the food becomes scarce, during this time of the year is the only time Red Leaf monkeys will feed on mature leaves.
During April, June, and August, are the months when the Red Leaf monkeys consumed top soil of termite mounds. As they ate the termite mounds, they left the termites alone and only ate that of the dirt. This is the way for Red Leaf monkeys to obtain the minerals needed for a balance diet. The termite mound soil has high levels of calcium and magnesium. This soil is very acidic and has a dominant exchanging of cations, due to the aluminium that has been highly leached. Eating of the soil, they are maintaining the balance of minerals by also having a source of potassium and phosphorus. The reason they may be eating termite mounds rather than the soil around the bed of the forest, is because of the construction of the soil due to the termite's saliva. Termite soil has higher nutrient content than that of the bed soil. This foraging mechanism helps them obtain the scarce nutrients and have a balance diet of plant matter and minerals.
Since Red Leaf monkeys are from Southeast Asia, this means they must endure the scarcity of fruit due to the unpredictable time period of the releasing fruits. Red Leaf monkeys spends around half their time eating that of leafy greens and the other half in eating seeds and fruits. They favor the digestibility that is high within leaves, which has a fiber level that is relatively low. They combine young leaves with flowers to incorporate protein in high levels. Fruits and seeds allows them to have a concentration that contains high levels of fats or carbohydrates, that is to be stored. The Red Leaf monkeys only eat from rare trees as well as lianas. They must rely on fallback resources during the time that involves the lack of food intake. A 25-month (May to October) observation was conducted, G. Hanya and H. Bernard observed their behavior and surveyed their phenology and vegetation, as well as conducting a chemical analysis which compared leaves that were eaten with the nonfood leaves. During this time, they observed the Red Leaf Monkeys "spending 46 percent of their feeding time on young leaves, 38 percent on seeds, 12 percent on whole fruits, 2.0 percent on flowers, 1.0 percent on bark, and 1.2 percent on pith." 
The forest they are located is within the Danum Valley of eastern Sabah, northern Borneo, had rainfall of 3115 millimeter between the year 2007 and 2008. The temperature of this year had a range of 31.4 °C being the maximum, 22.5 °C with the minimum, and the mean being that of almost 27 °C. With their chemical analysis, they had sampled the leaves of having 20 different species being in abundance. But only seven of those species were actually being consumed, leaving the rest (16) not having been consumed. During the time between April and October 2007, there was an increase of the percentage in fruiting trees. Whereas, the year of 2008 had a significant drop of the percentage of fruiting trees due to the lack of water consumption. With this change of climate, the Red Leaf monkey had to rely on the fallback resources to sustain them.
When the time produced a high amount of seeds and fruits, they spent most of their feeding time eating that of what they desired. Due to the lack of water intake of the fruits, they are unable to produce those that the Red Leaf monkey enjoys to eat and they must fallback on what is available. During the time that they must fallback on the resources, they would feed on young leaves that are from a flowering plant known as Spatholobus macropterus. This species of plants are very important to their diet. It has had the total feeding time of 27.6 percent. The leaves that had been consumed had more protein than those that were not consumed. Red Leaf monkeys would feed on different types of leaves due to their abundance. This selection of containing fallback foods of leaves, was in an appearance of the fact that they were trying to obtain both nutrition as well as abundance. When there is an increase of availability of fruits, Red Leaf monkeys expands the time of feeding on seeds by 18 times. As the availability of fruit increases, Red Leaf monkeys' time of feeding raises around 28 percent. With this increase of availability, they eat more species and plants. The seeds within the fruits and plants then become consumed as they feed on these different species of plants and fruits.
- Groves, C.P. (2005). Wilson, D.E.; Reeder, D.M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. p. 172. ISBN 0-801-88221-4. OCLC 62265494.
- Nijman, V. & Meijaard, E. (2008). "Presbytis rubicunda". The IUCN Red List of Threatened Species. 2008: e.T18131A7667504. doi:10.2305/IUCN.UK.2008.RLTS.T18131A7667504.en.
- Hanya, Goro; Bernard, Henry (2012). "Fallback Foods of Red Leaf Monkeys (Presbytis rubicunda) in Danum Valley, Borneo". Int J Primatol. 33 (2): 322–337. doi:10.1007/s10764-012-9580-9.
- Bennett, Elizabeth L.; Davies, A. Glyn; Waterman, Peter G. (1987). "Food selection by two South-east Asian colobine monkeys (Presbytis rubicunda and Presbytis melalophos) in relation to plant chemistry". Biological Journal of the Linnean Society. 34: 33–56. doi:10.1111/j.1095-8312.1988.tb01947.x.
- Supriatna, Jatna; Soekara, Endang; Manullang, Barita O. (1986). "Group composition, home range, and diet of the Maroon leaf monkey (Presbytis rubicunda) at Tanjung Puting reserve, Central Kalimantan, Indonesia". Primates. 27 (2): 185–190. doi:10.1007/BF02382597.
- Davies, A. G.; Baillie, I. C. (1988). "Soil-eating by red leaf monkeys (Presbytis rubicunda)in Sabah, Northern Borneo". Biotropica. 20 (Association for Tropical Biology and Conservation): 252–258. doi:10.2307/2388241. JSTOR 2388241.
- Hanya, Goro; Bernard, Henry (2013). "Functional response to fruiting seasonality by a primate seed predator, red leaf monkey (Presbytis rubicunda)". Tropical Ecology. 54: 383–395.
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